Electric motor.



116.844,?01: PATENTED FEB. 19, 1907.

J. B. WANTZ.

ELECTRIC MOTQR. APPLICATION FILED FEB. 2a, 1806'.

ZSHBBTS-SHEET 1.

No. 844,701. PATENTED FEB. i9 19ov.

J. B. WANTZ'.

ELECTRIC MOTOR.

APPLICATION FILED FEB. 23, 1906.

2 SHEETS-411mm 2.

mg to the character UNITED STATES I ATENT OFFICE.

JULIUS B. WANTZ, OF CHICAGO, ILLINOIS, ASSIGNOR TO VICTOR ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTRIC MOTOR.

Specification of Letters Patent.

Patented Feb. 19. 1907.

Application filed February 23, 1906. Serial No, 302,462.

Motor, of which the following is a specifieatron.

My object is to provide an electric motor of improved construction adapting it for the convenient use of dentists and others to 0pcrate flexible shafts bufling wheels or other attachments which it is desired to rotate at different speeds, accordof the work to be performed.

In-carrying out my invention I provide the motor with improved speed changing and controlling switch mechanism.

In the drawings, Figure 1 is a vertical section through the device; Fig. 2, a plan view of the improved speed-controlling switch mechanism; Figs. 3 and 4, enlarged broken sections taken, respectively, on lines 6 and 7 in Fig. 2 and viewed as indicated by the ar rows; and Fig. 5, a broken diagrammatic view of the switc mechanism, circuit, and resistance. i

The motor has a close dust-proof shell con- 'sisting of the main or body portion 9 and ends-or caps 10 and 11, fastened thereto with screws, as indicated. The body portion 9 would contain the field-magnets not shown) and is mounted upon a hollow base 12, provided with a removable bottom plate 13. The armature 14'1s upon an armature-shaft 15, carrying the commutator 16.

In the hollow base 12 is a platform 40, of slate or other insulating material, fastened screws against depending lugs 41. Mountc(. on the platform are bearings 42 and 43 for a rotary shaft 44, which passes outward througl the casing and is provided at its outer end with a thumb-wheel 45 and indicator-collar 46. Surrounding and secured to the shaft 44 between the bearings 42 and 43 are spacing sleeves or nuts 17, which clamp between them in the positions shown a cam 48, of insulating material, having an abrupt shoulder 49 and depressed portion 50, short cams or segments 51, 52, and 53, of conducting material, and a ratchet-wheel 54 of conducting rhetoric]. The cams 51, 52, and 53 are fastened, as indicated, to extend at ro- *rcssive angles, the cam 48 and ratchet-w eel or to hold grinding or.

54 being mounted upon the shaft according to an arbitrary arrangement relative to the intermediate cams. On the platform is a contact-post 55,

line-wire 56.

I 57 1s a spring fastened by {screws to the plat-form, as shown in Fig. -1, and having a shoulder 58 in the path of the l cam 48.

and 53, respectively, are cont;=.ctsprings 59, 60, and 61, all mounted upon the platform, as shown, and also mounted upon the platform is a spring-contact dog 62, hearing against the ratchet-wheel 54. 63 is a resistance coil or tube. It is illustrated as a tube in Figs. 1 and 5 and by resistince coils in the diagranr Fig. 5 fonpurposcs of illustration.

forming the terminal of a In the paths of the cams 51, 52,

As shown ntost plainly in the diagram Fig. 8, the spring-contacts 57 and 59 are connectcd directly with a wire 64, leading to one brush of the niotor, and the s ring-contact I 62 is connected with a wire 65, eading t0 the held of the n1otor. The contacts 57 and 59 I are also connected to one end of the resist- I ance 63, while the contact 62 is connected with the opposite end of the resistance. The contacts 60 and 61 are connected with the resistance at di'll'crcnt points between its ends. When the shaft-rotating handle or thumbpiece 45 is turnedto carry the alzrupt shoulder 49 of the cam 48 *hich cam is of vulcanized fiber or other insulating material) beyond the shoulder 58 of the spring 57, the said shoulder 58 springs into the recessed or depressed portion 50, thus breaking the eontact between the said spring and the post 55. This breaks the current from the line-wire 56 to the motor. Turning of the shaft 44 to cause. the contact or dog 62 to engage the next tooth of the ratchet 54 causes the first cam 51 to engage the contact 59-and the cam 48 to press the spring 57 upon the post 55. This causes the current from the wire 56 to pass through the post 55, spring 57, and wire 64 through the armature 14 and out to the line-wire 66. Current is shunted through the cam 51, shaft 44;ratchet 54, dog 62, and wire 65 through the motorfield to the line-wire 66. The effect of this 1 first partial turning of the shaft is toclose the direct and shunt circuits, but to cut he resistance into the shunt-circuit, and the motor will be caused to runat slow or first speed. Further turningofthe shaft to cause the dog l to engage the next notch of tie ratchet 54 causes the cam 51 to release the contactspring 59 andthe next cam 52 to he brought into engagement with the contactespring 60. This causes the shunt-circuit to pass over the. contact-spring 57 through the first division of the resistance 63 to the contactespring 60, thence through the cam 52, shaft 44, ratchet 54, and dog 62 to the field. T he current thus weakened to the extent of the first division of the resistance 63 weakens the field-magnets accordingly and to that extent effects an increase in speed of rotation of the armature. Further turning of the shaft to cause the dog 62 to engage the next tooth of the ratchet causes the cam 52 to release the contact-spring {50 and the cam 53 to engage the contact-spring 61. This cuts in two divisions of the resistance 63, and consequently i icreases the speed of rotation of the armature :itccordingly. Still further turning of the shaft until the dog 62 engages the next tooth. oi the ratchet 54 causes the cam 53 to disengage the contact 61, whereh y the entire resistance is cut in, tl e shunt-current pass- 5 ing rrom the spring 57 through the resistance to the motor lield, thereby weakening the latter to an extent which causes the armature to rotate at the highest speed, according to the well-known lawsgoverning changes of speed hrought about in the manner stated. in the final partial turning of the shaft to cause the dog 62 to engage the next tooth of the ratchet th abrupt shoulder ll) of the cam 48 passes the shoulder 58 of the contact spring 57, permitting saidcontact to spring suddenly out engagement with the terminal 55, and thus break the circuit and stop the motor.

it will understood from the foregoing description that the shaft 44 can he turned in but one direction, and each tooth of the ratchet marks a change in operation. in breaking the circuit the contact-spring jumps tl'ierewith both included in the shunt-circuit,

witn such speed from the terminal while the dog is leaving one tooth of the ratchet for anotherthat 11o spark will be drawnhy' the contact-spring; In fact, in the operatian of my improved switch device the danger of sparkdrawing is entirely eliminated.

Whatl claim as new, and desire to secure, by LettersPatent, is

1. The starting and stopping switch device for an electric motor comprising in combination a rotary shaft, a line-wire terminal, a normally open contact-spring movable into and out of engagement: with said terminal and'from which extends a direct armaturecircuit, and a motor-field shuntcircuit, a ratchet on theshait, and a dog cooperating 60 and a cam on the shaft shaped and movable to close said s ring against said. terminal and to permit su den circuit-breaking resilience of the contact-spring.

2. The starting, I stopping and speedchanging switch device for an electric motor, comprising in combination al'otary shaft, 8. line-wire terminal, a normally open-contactspring movable into and out of engagement with said terminal andirom which extends a direct armature-circuit and a motor-field shunt-circuit, a ratchet on the shaft and a dog cooperating therewith both included in the shunt-circuit, a camon the'shaft having an abrupt shoulder and en aging said contact-spring with the termina until said shoulder clears said contact, a resistance coiiperating with said shuntcircuit, and contactspring engaging and releasing cams on the shalt operating in series in the rotation of the shaft to cut in divisions of said resistan e, substantially as and for the purpose set forth.

JULIUS B. WANTEZ.

In presence of-- J. H. Lnnnns, G. A. Cnsrrron. 

